Wow! I generally have to say it raises my interest. Some people are just really good at flirting and being friendly and to the extent I can believe that I *might* win this woman's full attention, it just makes it more worth the effort.
When I am *with* a woman (in a relationship) I love it when she flirts (classily) with others... "save the last dance for me" is my motto... If I take a woman to a dance, I enjoy it if she dances with others (as I will if she is) and then at the end of the night (and sometimes along the way), we will take time to check in with one another, etc.
Of *course* I don't want to be abused, neglected or two-timed... it all has to be consensual and in good spirit!